The present invention is generally directed to improved devices, systems, and methods for treatment of the heart. Exemplary embodiments provide implants and methods for alleviating congestive heart failure and other progressive diseases of the heart. Congestive heart failure may, for example, be treated using one or more implants which are selectively positioned relative to a septum and wall of the heart so as to exclude scar tissue and limit a cross section across a ventricle. Trauma to the heart tissues may be inhibited by decreasing a size of the heart chamber and/or approximating tissues when stress on the tissues is limited. Implant locations and overall chamber remodeling achieved by a plurality of implants may be determined so as to provide a beneficial volumetric chamber shape. Exemplary axially curved catheter bodies may enhance measurements for and implant positioning control over such remodeling.
Congestive heart failure (sometimes referred to as “CHF” or “heart failure”) is a condition in which the heart does not pump enough blood to the body's other organs. Congestive heart failure may in some cases result from narrowing of the arteries that supply blood to the heart muscle, high blood pressure, heart valve dysfunctions due to rheumatic fever or other causes, cardiomyopathy (a primary disease of the heart muscle itself), congenital heart defects, infections of the heart tissues, and the like. However, in most cases congestive heart failure may be triggered by a heart attack or myocardial infarction. Heart attacks can cause scar tissue that interferes with the heart muscle's healthy function, and that scar tissue can progressively replace more and more of the heart tissue. More specifically, the presence of the scar may lead to a compensatory neuro-hormonal response by the remaining, non-infarcted myocardium.
People with heart failure may have difficulty exerting themselves, often becoming short of breath, tired, and the like. As blood flow out of the heart slows, blood returning to the heart through the vascular system decreases, causing congestion in the tissues. Edema or swelling may occur in the legs and ankles, as well as other parts of the body. Fluid may also collect in the lungs, interfering with breathing (especially when lying down). Congestive heart failure may also decrease the ability of the kidneys to remove sodium and water, and the fluid buildup may be sufficient to cause substantial weight gain. With progression of the disease, this destructive sequence of events can cause the eventual failure of the remaining functional heart muscle.
Treatments for congestive heart failure may involve rest, dietary changes, and modified daily activities. Various drugs may also be used to alleviate detrimental effects of congestive heart failure, such as by expanding blood vessels, improving and/or increasing pumping of the remaining healthy heart tissue, increasing the elimination of waste fluids, and the like.
Surgical interventions have also been applied for treatment of congestive heart failure. If the heart failure is related to an abnormal heart valve, the valve may be surgically replaced or repaired. Techniques also exist for exclusion of the scar and volume reduction of the ventricle. These techniques may involve (for example) surgical left ventricular reconstruction, ventricular restoration, the Dor procedure, and the like. If the heart becomes sufficiently damaged, even more drastic surgery may be considered. For example, a heart transplant may be the most viable option for some patients. These surgical therapies can be at least partially effective, but typically involve substantial patient trauma. While people with mild or moderate congestive heart failure may benefit from these known techniques to alleviate the symptoms and/or slow the progression of the disease, less traumatic therapies which significantly increase the heart function and extend life of congestive heart failure patients has remained a goal.
It has recently been proposed that an insert or implant be placed in the heart of patients with congestive heart failure so as to reduce ventricular volume. With congestive heart failure, the left ventricle often dilates or increases in size. This can result in a significant increase in wall tension and stress. With disease progression, the volume within the left ventricle gradually increases and blood flow gradually decreases, with scar tissue often taking up a greater and greater portion of the ventricle wall. By implanting a device which brings opposed walls of the ventricle into contact with one another, a portion of the ventricle may be constricted or closed off. By reducing the overall size of the ventricle, particularly by reducing the portion of the functioning ventricle chamber defined by scar tissue, the heart function may be significantly increased and the effects of disease progression at least temporarily reversed, halted, and/or slowed.
An exemplary method and implant for closing off a lower portion of a heart ventricle is shown in FIG. 1, and is more fully described in U.S. Pat. No. 6,776,754, the full disclosure of which is incorporated herein by reference. As illustrated in FIG. 1, a patient's heart 24 has been treated by deployment of an implant across a lower portion of the left ventricle 32 between septum 28 and a left wall or myocardium region 34. The implant generally includes a tensile member which extends between anchors 36 and 38.
A variety of alternative implant structures and methods have also been proposed for treatment of the heart. U.S. Pat. No. 6,059,715 is directed to a heart wall tension reduction apparatus. U.S. Pat. No. 6,162,168 also describes a heart wall tension reduction apparatus, while U.S. Pat. No. 6,125,852 describes minimally-invasive devices and methods for treatment of congestive heart failure, at least some of which involve reshaping an outer wall of the patient's heart so as to reduce the transverse dimension of the left ventricle. U.S. Pat. No. 6,616,684 describes endovascular splinting devices and methods, while U.S. Pat. No. 6,808,488 describes external stress reduction devices and methods that may create a heart wall shape change. Each of these patents is also incorporated herein by reference.
While these and other proposed implants may help surgically remedy the size of the ventricle as a treatment of congestive heart failure and appear to offer benefits for many patients, still further advances would be desirable. In general, it would be desirable to provide improved devices, systems, and methods for treatment of congestive heart failure and other disease conditions of the heart. It would be particularly desirable if such devices and techniques could increase the overall therapeutic benefit for patients in which they are implanted, and/or could increase the number of patients who might benefit from these recently proposed therapies. Ideally, at least some embodiments would include structures and or methods for prophylactic use, potentially altogether avoiding some or all of the deleterious symptoms of congestive heart failure after a patient has a heart attack, but before foreseeable disease progression. It would be advantageous if these improvements could be provided without overly complicating the device implantation procedure or increasing the trauma to the patient undergoing the surgery, ideally while significantly enhancing the benefits provided by the implanted device.